Leakage preventing microwave oven

ABSTRACT

A microwave oven comprising a door lock key operatively associated with a door handle of a door hermetically sealed to block off the escape of microwave energy, and a door lock switch operated by said door lock key, whereby instantaneous leakage of microwave energy is prevented when said door is opened in the course of heating.

I a v United States Patent 1 1 1 1 3,794,797 Nakano Feb. 26, 1974 LEAKAGE PREVENTING MICROWAVE 5,715,552 2/1973 Umezu et a1 219/1055 OVEN 3,715,554 2 1973 Umezu et 211.... 219/1055 3,196,242 7/1965 DeVries et al.. 219/1055 [7 Inventor: Mlchlyo a Nara, Japan 3,576,417 4/1971 Tingley 219/1055 [73] Assignee: Matsushita Electric Industrial Co.,

Ltd., Osaka, Japan Primary Examiner-C. L. Albritton Assistant Examiner-Hugh D. Jaeger [22] Flled' 1972 Att0rney, Agent, or Firm-Stevens, Davis, Miller & [21] App]. No.: 244,057 Mosher [30] Foreign Application Priority Data [57] ABSTRACT Apr. 19, 1971 Japan 46-25495 A microwave oven comprising a door lock key operatively associated with a door handle of a door hermeti- [52] US. Cl. 219/1055 ally sealed to block off the escape of microwave en- [51] Int. Cl. H05!) 9/06 ergy, and a door lock switch operated by said dOOr [58] F|eld of Search 219/1055 lock key, whereby instantaneous leakage of microwave energy is prevented when said door is opened in [56] References Cited the course of heating.

UNITED STATES PATENTS 3182164 5/1965 6 Claims, 5 Drawing Figures lronfield 219/1055 PATEN-TEDFEBZB 1974 3 794 797 sum 1 or 3 FIG PATENIEOmzs la v 37945197 sum 3 or 3 LEAKAGE PREVENTING MICROWAVE OVEN The present invention relates to a mechanism for microwave ovens which is designed to prevent the escape of microwave energy.

It is an object of the present invention to provide a microwave oven comprising a door handle provided with a movable member, and door lock key operatively associated with the movable member, whereby a door lock switch is operated by the door lock key thereby preventing instantaneous leakage of microwave energy upon the opening of the door in the course of heating.

It is another object of the present invention to provide a microwave oven in which a pantograph mechanism is disposed in the door handle and the door lock key is operated through the pantograph mechanism ensuring a uniform operating stroke therefor irrespective of whatever portion of the door handle is gripped.

It is a further object of the present invention to provide a microwave oven in which the movable member of the door handle is disposed in parallel to the longitudinal length of the door handle and thus said movable member serves to ensure a uniform operating stroke for the door lock key.

It is a still further object of the present invention to provide a door lock mechanism in which the door lock key is made of a lower permitivity material and extendible through a portion of a choke cavity, thereby simplifying the mounting of the door lock key and thus making the mechanism inexpensive to manufacture and compact in construction.

The above and other objects and advantages of the present invention will be made more apparent from the following description of the preferred embodiment of the invention taken in conjunction with the accompanying drawings, in which;

FIG. 1 is a perspective view of a microwaveoven according to the present invention;

FIG. 2 is a longitudinal sectional view of the microwave oven shown in FIG. 1;

FIG. 3 is an exploded view of the door portion constituting the principal part of the oven of FIG. 1;

FIG. 4 is a perspective view of the door portion of FIG. 3 with a part broken away; and

FIG. 5 is a sectional view taken on the line X-X of FIG. 4.

Referring now to the drawings, numeral 1 designates an oven proper; 2 aheating, cavity formed within the oven 1 and provided with a door 3 pivotably mounted by a hinge 4 at the front opening thereof.

A choke cavity 5 is provided in the marginal edges of the door 3 forming part thereof and the choke cavity 5 constitutes with a back plate 6 a microwave attentuating choke, with letters a and b in FIG. 2 denoting the depth of the choke cavity 5 which is selected to be one-quarter wavelength of the frequency used.

Numeral 7 designates a door lock key made of a material, such as, polypropylene whose loss due to high frequencies is not great. The door lock key 7 is mounted so that it is extendible through the choke cavity 5 out of the upper face of the door 3 and a door lock switch 8 is mounted on that side of the oven proper 1 which opposes the door lock key 7.

Numeral 9 designates the handle of the door 3 comprising a handle grip 11 and a movable member 10. A pantograph mechanism mounted within the door handle 9 is operatively associated with the movable member 10 of the handle 9, so that the door lock key 7 is moved vertically by a lever 13 mounted in the door 3 thereby opening and closing the door lock switch 8. The door lock key is normally biased upwardly by a spring 14.

The lever 13 is L-shaped and its hooked portion is mounted at a pivot 14'. One end of the lever 13 is also fitted into the door lock key 7 at the lower end thereof and the other end engages with one end of a lever 15 of the pantograph mechanism 12.

Numeral 16 designates a magnetron mounted on the upper face of the heating cavity 2, and numeral 17 desi'gnates a material to be cooked.

With the construction described above, if the user trys to open the door 3 in the course of cooking, the instant the user holds the handle grip l1 and movable member 10, the movable member 10 is moved into the handle grip 11 compressing the pantograph mechanism 12 and thus moving the free end of the lever 15 in the direction of an arrow in FIG. 4. Consequently, the lever 13 is moved downwardly about the pivot 14' (in the direction of the arrow) causing the door lock key 7 to move downwardly against the spring force of the spring 14.

. When this occurs, the door lock switch 8 which has been pressed by the upper end of the door lock key 7 is turned off so that the door 3 is opened after the interruption of the power supply circuit. Thus, leakage of microwave energy upon the opening of the door can be prevented.

In conclusion, it is seen that according to the present invention described hereinbefore, a simple operation of holding and pulling the handle grip of the door can open the door and at the same time prevent microwave leakage, while the use of a simple pantograph mechanism ensures a uniform operating stroke of the door lock key regardless of whatever part of the door handle is pulled by the user, thus providing a microwave oven which is compact in construction, highly reliable in operation and convenient to use.

Furthermore, the door lock key is provided across the choke, so that there is a simplification in the choke and the door lock mechanism, providing a door structure which is inexpensive to manufacture and compact in construction.

What is claimed is:

l. A microwave oven comprising an enclosure housing a heating cavity, a door pivotably mounted at the front opening of said heating cavity, a door handle with a movable member and a pantograph mechanism, a door lock key movably associated through said pantograph mechanism with said movable member, a choke cavity formed within a marginal portion of said door, said door lock key being extensible through said'choke cavity and an aperture in one side face of said marginal portion to the exterior of said door, and a door lock switch located on said enclosure in operative relation to said door lock key.

2. A microwave oven according to claim 1 wherein said door handle comprises a fixed handle grip portion and a movable handle grip portion which extend in a horizontally transversal direction with respect to said door, said movable handle grip portion being adapted to be movable in the normal direction to said fixed portion and having a larger grip area than that of said fixed portion, said movable member including said movable handle grip portion.

3. A microwave oven according to claim 1 wherein said door lock key is made of a dielectric material.

4. A microwave oven according to claim 1 wherein said choke cavity is of a thin thickness having a onefourth wavelength, and connecting means is provided inside of said choke cavity in a hollow space of said door, said connecting means connecting said pantograph mechanism and said door lock key.

5. A microwave oven according to claim 4 wherein said door lock key is formed of a straight key made of a dielectric material, and said key is movably mounted via spring means on said door, said spring means biasing said key in a direction such that said movable mem ber is restored to its normal position where said door closes said front opening of said heating cavity.

6. A microwave oven comprising an enclosure hous ing a heating cavity; a door pivotably mounted at the front opening of said heating cavity, said door having an inner, hollow space surrounded by front, back and side walls of the door; a door lock key; a door handle having a pantograph mechanism, said door handle including first and second portions extending parallel to the door, at least one of said portions being movably mounted in a direction normal to the other, said pantograph mechanism incluidng two levers pivoted at their central parts and mounted between said first and sec end portions so that said one of said first and second portions which moves in the normal direction compresses or expands said pantograph mechanism, one of said levers having one end extending through said front wall into said inner hollow'space where said one end is engaged through an L-shaped lever with said door lock key in which said L-shaped lever is pivoted at its bent section, said one end being made to abut against one end of said L-shaped lever, the other end of said L- shaped lever being inserted in a through hole formed at one end of said door lock key to reciprocate said key in response to the compression or expansion of said pantograph mechanism; means [for always biasing said door lock key in one predetermined direction and, in turn, said one of said first and second portions in a direction such that said first and second portions are apart from each other; a choke cavity formed within a marginal portion of said door, said door lock key being extensible through said choke cavity and an aperture on one side face. of said marginal portion tothe exterior of said door; and a door lock switch located on said enclosure in operative relation'to said door lock. key. 

1. A microwave oven comprising an enclosure housing a heating cavity, a door pivotably mounted at the front opening of said heating cavity, a door handle with a movable member and a pantograph mechanism, a door lock key movably associated through said pantograph mechanism with said movable member, a choke cavity formed within a marginal portion of said door, said door lock key being extensible through said choke cavity and an aperture in one side face of said marginal portion to the exterior of said door, and a door lock switch located on said enclosure in operative relation to said door lock key.
 2. A microwave oven according to claim 1 wherein said door handle comprises a fixed handle grip portion and a movable handle grip portion which extend in a horizontally transversal direction with respect to said door, said movable handle grip portion being adapted to be movable in the normal direction to said fixed portion and having a larger grip area than that of said fixed portion, said movable member including said movable handle grip portion.
 3. A microwave oven according to claim 1 wherein said door lock key is made of a dielectric material.
 4. A microwave oven according to claim 1 wherein said choke cavity is of a thin thickness having a one-fourth wavelength, and connecting means is provided inside of said choke cavity in a hollow space of said door, said connecting means connecting said pantograph mechanism and said door lock key.
 5. A microwave oven according to claim 4 wherein said door lock key is formed of a straight key made of a dielectric material, and said key is movably mounted via spring means on said door, said spring means biasing said key in a direction such that said movable member is restored to its normal position where said door closes said front opening of said heating cavity.
 6. A microwave oven comprising an enclosure housing a heating cavity; a door pivotably mounted at the front opening of said heating cavity, said door having an inner, hollow space surrounded by front, back and side walls of the door; a door lock key; a door handle having a pantograph mechanism, said door handle including first and second portions extending parallel to the door, at least one of said portions being movably mounted in a direction normal to the other, said pantograph mechanism incluidng two levers pivoted at their central parts and mounted between said first and second portions so that said one of said first and second portions which moves in the normal direction compresses or expands said pantograph mechanism, one of said levers having one end extending through said front wall into said inner hollow space where said one end is engaged through an L-shaped lever with said door lock key in which said L-shaped lever is pivoted at its bent section, said one end being made to abut against one end of said L-shaped lever, the other end of said L-shaped lever being inserted in a through hole formed at one end of said door lock key to reciprocate said key in response to the compression or expansion of said pantograph mechanism; means for always biasing said door lock key in one predetermined direction and, in turn, said one of said first and second portions in a direction such that said first and second portions are apart from each other; a choke cavity formed within a marginal portion of said door, said door lock key being extensible through said choke cavity and an aperture on one side face of said marginal portion to the exterior of said door; and a door lock switch located on said enclosure in operative relation to said door lock key. 